If you are concerned these may be too spicy for a child's palate, you can reduce the chile or omit it, fill a couple of pops containers with the unspiced mixture, then stir in a little to make the rest of the batch with kick. My suggestion: just go for it. The pops are sweet and you may find that your child enjoys them even with the spice.
Mango Popsicles (with a kick)
1 Cup mango juice or nectar
1/4 Cup sugar
2 teaspoons lemon juice
1 teaspoon ancho chili powder
1 large mango
Heat mango juice, sugar, lemon juice and 1/2 Cup water in a saucepan, stirring until sugar dissolves. Transfer to a bowl. Chill in fridge.
Peel and seed mango and cut it into small cubes. Stir the chili powder and mango pieces into the liquid. Pour into ice pop molds. Insert popsicle stick. Freeze until solid (at least 3 hours).